Uncapping
From Free net encyclopedia
Uncapping, in the context of cable modems, refers to a number of activities performed to alter one's internet service provider modem settings. It is sometimes done for the sake of bandwidth (i.e. by buying a 512kbit/s access modem and then altering it to 10Mbit/s), pluggable interfaces (as by using more than one public ID), or any configurable options a DOCSIS modem can offer.
Uncapping is an illegal activity and many internet service providers check modem configuation files nightly to detect uncapped modems. If caught uncappers risk possible account termination and/or prosecution for theft of service.
Methods
There are several methods used to uncap a cable modem, by hardware or software tricks.
The first technique to enjoy any success employed Motorola modems (such as SB3100, SB4100 and some of the SB4200 models). By spoofing the TFTP server, one could force the modem to accept a different config file than would be expected. The config file is a file stored on the TFTP server that tells your modem the download and upload caps for it. An example of spoofing would be to edit the config file (Requires a DOCSIS editor) or replacing your config file with one from a faster modem (Through Gnutella Networks). Refer to http://www.cable-modems.org/articles/uncapping/ for more information.
An alternate method employs dhcpforce. By flooding a modem with faked DHCP packets (which contain configuration filename, TFTP IP, etc), one can convince the modem to accept any desired config file, even on one's own server (provided the server is routed, of course).